Swash plate compressor

ABSTRACT

A swash plate compressor for use in refrigerators operating with a refrigerant gas in which is previously mixed lubricating oil, characterized in that a crank case of the compressor is so arranged as to constitute part of a low pressure passage connected to the inlet side of the compressor, and said low pressure passage is communicated with portions of the compressor which requires the supply of lubricating oil.

United States Patent Kishi et al. 1 Sept. 9, 1975 1 SWASH PLATECOMPRESSOR 3,352,485 11/1967 Niki et a1 417/269 [75] inventors: AtsuoKishi; Takashi Degawa, both 3 712,759 1973 32:? 7:269

0f Katsula. Japan 3,785,751 1 1974 Nemoto et a1.. 417/269 [73] Assign:Hitachi, Md" Japan 3,801,227 4/1974 Nakayama 417/269 1 May 1973 PrimaryExaminerWil1iam L. Freeh Appl. No.: 358,334

[30] Foreign Application Priority Data May 10, 1972 Japan 47-45445 [52]U.S. Cl. 417/269 [51] Int. Cl. F041) 27/08 [58] Field of Search 417/269[56] References Cited UNITED STATES PATENTS 2,877,653 3/1959 Masnik eta1. 74/60 3,057,545 10/1962 Ranson ct al. 417/269 Assistant ExaminerG.P. LaPointe Attorney, Agent, or FirmCraig & Antonelli 5 7 ABSTRACT Aswash plate compressor for use in refrigerators operating with arefrigerant gas in which is previously mixed lubricating oil,characterized in that a crank case of the compressor is so arranged asto constitute part of a low pressure passage connected to the inlet sideof the compressor, and said low pressure passage is communicated withportions of the compressor which requires the supply of lubricating oil.

16 Claims, 4 Drawing Figures PATENIEBSEP 91975 3,904,320

SHEET 1 [1F 3 FIG! PATENTEBSEP ems 3,904,320

sum 3 OF 3 SWASH PLATE COMPRESSOR BACKGROUND OF THE INVENTION Thisinvention relates to improvements in the lubrication of a swash platecompressor for refrigerators, and more specifically to a swash platecompressor for refrigerators which is so designed that the lubricationof parts calling for lubrication is achieved by lubricating oilpreviously mixed in refrigerant gas, by taking advantage of the flow ofsaid refrigerant gas without providing an oil pan or oil pump in thecompressor The refrigeration cycle of a refrigerator is composedgenerally of a compressor, a condenser, a liquid receptacle, anexpansion valve, an evaporator and a piping interconnecting theseelements. In the operation, a refrigerant is compressed in thecompressor, cooled and liquefied in the condenser, accumulatedtemperarily in the liquid receptacle, reduced in pressure during passagethrough the expansion valve, again gasified in the evaporator andreturned to the compressor.

Swash plate compressors generally have an oil reser voir at the bottomof the crank case, and oil accumulated in said oil reservoir is suppliedby a gear pump or the like to bearings, pistons and other slidingmembers. With such a construction, however, the oil intrudes, though ina very small amount, into the refrigeration cycle-constituting passagethrough gaps between the piston and cylinder wall and at other portionsduring the suction and compression of the refrigerant gas, andeventually the oil in the oil reservoir would be exhausted unless theoil is separated and recovered from the refrigerant. Therefore, it hasbeen usual to separate the oil from the refrigerant in the inlet passageof the compressor and collect the separated oil in the oil reservoir.

In such arrangement, however, a high degree of vacuum pressure suddenlydevelops in the inlet passage at the start of the compressor, which actsin the oil reservoir through the gap between the piston and cylinderwall of the compressor or an oil recovery passage, causing boiling ofthe lubricating oil in said oil reservoir or the so-called oil foaming.Once the oil foaming phenomenon has occurred, the oil abruptly intrudesinto the inlet passage through the aforesaid gap or oil recoverypassage, with the result that the oil reservoir becomes emptied andbinding of the bearings and other sliding parts results. Further, whenthe vacuum pressure appears in the inlet passage, the internal pressureof the oil pan also decreases, impairing substantially the performanceof the gear pump and inducing the same trouble.

These problems are inevitable in the type of compressor in which oil isaccumulated in a predetermined amount in an oil reservoir and suppliedto the sliding parts by means of a pump or the like.

As a countermeasure, it is conceivable to make the oil reservoir largefor storing a larger amount of oil therein, but increasing the size ofthe oil reservoir results in an increase in size of the compressor. Thisis undesirable for compressors intended to be used in refrig' erators,particularly in car coolers and air conditioners, which have a limitedspace for mounting the compres SOI'.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a swash plate compressor for use in refrigerators, which doesnot pose a lubricating oil shortage problem at the start of and under avacuum pressure condition of the compressor.

Another object of the invention is to provide a swash plate compressorfor use in refrigerators, which is so designed that the lubrication andcooling of parts required to be lubricated and cooled can be achievedwithout requiring an oil reservoir or oil pump.

Still another object of the invention is to provide a swash platecompressor for use in refrigerators, which is small in size, and can bemanufactured at a low cost and mounted easily even in narrow spaces.

A further object of the invention is to provide a swash plate compressorfor use in refrigerators, which is so arranged that the internaltemperature rises uniformly, whereby the thermal deformation of thecompressor is made uniform and the occurrence of an abnormal pressure isavoided which would otherwise occur due to temperature rise.

According to the invention there is provided a swash plate compressor tobe used in the type of refrigerator using a refrigerant gas havinglubricating oil mixed therein beforehand, characterized in that a crankcase of the compressor constitutes part of a low pressure passageconnected to the inlet side of the compressor and said low pressurepassage is communicated with the portions in need of lubricating oilsupply.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view ofa compressor for refrigerators according to one embodiment of theinvention;

FIG. 2 is a sectional view taken on the line IIII of FIG. 1;

FIG. 3 is a sectional view taken on the line llllll of FIG. 2; and

FIG. 4 is a vertical sectional view of another embodiment of thecompressor for refrigerator according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The practical construction ofthe compressor according to the invention will be described by way ofexample with reference to the drawings. In FIGS. 1 to 3, referencenumerals ll, 11' designate a pair of cylinder blocks disposed in a shell19 in opposed relation, with a swash plate 12 interposed therebetween. Adrive shaft 13 is rotatably supported in the cylinder blocks 11, 11 bybearings 14, 14', and the swash plate 12 is fixedly mounted on saiddrive shaft 13. The rotation of the drive shaft 13 is converted into areciprocal movement of pistons 15, 15' through the swash plate, slidingmembers l6, l6 and steel balls l7, 17, said pistons 15, l5 respectivelybeing slidably received in cylinder chambers 34, 34 formed in thecylinder blocks 1 I, ll A refrigerant gas flows into a crank case 21from an inlet pipe 18 through a low pressure passageforming inlet port20 defined by the cylinder blocks 11, 11', and sucked into low pressurechambers 25, respec tively formed in a front cover 23 and a rear cover24, through low pressure passageforming openings 30, and 22, 22',respectively provided in the cylinder blocks 11, II, and thence throughlow pressure passage-forming outlet openings 31, 31' respectivelyprovided in cylinder heads 29, 29'. From the low pressure chambers 25,25', the refrigerant gas is sucked into the cylinder chambers 34, 34'through inlet openings 40 and compressed therein by the pistons l5, l5reciprocating in said cylinder chambers. The compressed pressurized gasis discharged into high pressure chambers 26, 26' through outletopenings 41. The pressurized gas collected in the high pressure chamber26' is discharged directly from an outlet pipe 28, while the pressurizedgas collected in the high pressure chamber 26 flows into die highpressure chamber 26' through a high pressure passage-forming conduit 27provided in the cylinder blocks 11, 11' and is discharged from theoutlet pipe 28.

Lubricating oil is previously mixed in the refrigerant gas forcirculation in the refrigeration cycle along therewith and, therefore,is sucked into the crank case 2] along with the refrigerant gas. in thecompressor, the lubricating oil is blown directly against the swashplate 12, the sliding members l6, 16', the steel balls l7, l7 and thrustbearings 10 to lubricate them. The major portion of the lubricating oilis sucked in the form of fine particles to be attached to the entiresurfaces of the sliding members, so that the quantity of lubricating oilcan be very small (of the order of several c.c./hour). Relatively largeparticles of the lubricating oilentraining liquid are divided intosmaller particles when they impinge against mainly the rotating swashplate, to suit them to movement to the sliding members and furtherportions in need of lubrication.

On the other hand, the lubrication of the bearings l4, l4 supporting thedrive shaft 13 is effected through small channels 33, 33'. Namely, thefine particles of oil which could not separate from the refrigerant gaswithin the crank case 21 pass in the low pressure passage-formingopenings 30, 30 and 22, 22', and a part thereof reaches the bearings 14,14' through the small channels 33, 33 to lubricate the same. Theremaining part of the fine particles of oil, which has not served thepurpose of lubrication, are sucked into the cylinder chambers 34, 34 anddischarged into the cycle along with the compressed gas through the highpressure passage-forming conduit 27 and the outlet pipe 28 to berecycled to the inlet pipe 18.

[n this case, the amount of oil sucked at the start of the compressor isvery small, unlike in the conventional compressors in which a largeamount of oil is exhausted as a result of oil-foaming under the effectof high degree of vacuum pressure developed suddenly on the inlet side.Therefore, the occurrence of abnormally high pressure within thecylinders due to the non-compressibility of oil can be avoided andthereby troubles such as breakage of pipe can be eliminated.

ln should be noted in particlar that, in the compressor of theinvention, the inlet pipe 18 is connected to the central portion of theshell 19 for communication with the crank case 21, and the low pressurepassageforming openings 30, 30' and 22, 22' are formed in the cylinderblocks 11, ll communicating the crank case 21 with the low pressurechambers 25, 25'. According to such construction, the flow direction ofthe refrigerant gas and the cross section of the flow passage changeabruptly within the crank case 21, during passage of the refrigerant gasfrom the inlet pipe 18 through the low pressure passage-forming inletport and openings 30, 30' and 22, 22', providing for effectiveseparation of the oil from the refrigerant gas. The oil thus separatedgoes into the clearances between the sliding members 16 and the swashplate, attaches to the surfaces of the steel balls l7, l7 and goes intothe thrust bearings l0, l0 and radial bearings 14, 14' to lubricate theengaging portions thereof. Further, the engaging portions of the swashplate 12 and the sliding members 16 where heat is generated most in thistype of compressor, are directly cooled by the refrigerant gas, so thatthe internal temperature rise of the compressor can be suppressed.

A swash plate compressor like that of the instant invention in which isemployed a spray lubrication method, does not require a gear pump whichis required by other types of compressor for the forced supply of oil.It should also be noted that according to the construction of theinstant invention, the particles of the cold oil are distributed toevery corners of the sliding parts to cool the same. This isadvantageous particularly in the operation of the compressor at highspeeds in that the thermal deformation of the parts becomes uniform.

In the conventional compressors, it has been necessary to providesealing means between the journal 35 of the shaft and the low pressurechamber to minimize the lubricating oil intruding into the low pressurecmaber therefrom. in the present invention, there is no necessity forsealingly isolating the journal 35 and the low pressure chamber 25 fromeach other. Therefore, the low pressure chambers 25, 25 and highpressure chambers 26, 26' can be formed in concentrical cylindricalshapes in the front cover 23 and rear cover 24. This means that theshape of the cylindrical front cover 23 and rear cover 24 can besubstantially simplified, it being only necessary to form par JiIaOnwalls 49 in the inside of said respective covers. 1 bus, according tothe present invention, the front cover 23 and rear cover 24 can beproduced by forging (these members have been produced by casting in thepast), which reduces the cost of manufacture of the compressor. Also, asstated, the low pressure chambers 25, 25' and high pressure chambers 26,26' formed in the front cover 23 and rear cover 24 can have the sameshape, which is extremely advantageous in the manufacture of thecompressor.

Further, in the present invention, the cylinder blocks 11, l l and thecylinder heads 29, 29' respectively also have the same shape, whichenhances the exchangeability of component parts. Further, since a gearpump and an oil pan are unnecessary, the fabrication of a gear pumpchamber and an oil passage bore in the drive shaft is not needed, whichrequires high precision. This also reduces the cost of manufacture ofthe compressor.

The formation of a mechanical seal chamber for accommodating the journal35 is also unnecessary. The elimination of the mechanical seal chamberand gear pump makes it possible to increase the volumes of the lowpressure chambers 25, 25' and high pressure chambers 26, 26', withoutincreasing the outer diameter of the compressor. This is effective, in acompressor of the type having about three cylinder chambers for high andlow pressure chambers, for smoothing the pulsations of incoming andoutgoing refrigerant gas and thereby enhancing the cooling efficiencyand reducing the noises of the refrigerator.

Swash plate compressors are frequently used in car coolers and car airconditioners. In this view, the compressor of the invention which doesnot require an oil pan is advantageous because it can be provided in acylindrical shape and can be installed in the engine room having alimited space, without subjecting to a limitation in its angularposition.

Another embodiment of the invention is shown in PK). 4. This embodimentis characterized by the construction of the high pressure passage 27.

Namely, the outlet pipe 28 similar to the inlet pipe 18 is providedcentrally of the shell 19 and high pressure passage-forming openings 27,27" are formed at por tions of the cylinder blocks 11, 11 respectively.On the other hand, a noise damping chamber 43 is formed between a cover42 fixed to the outer wall of the shell 19 and the shell 19, said noisedamping chamber being in communication with the openings 27, 27' throughcoil springs 50, 50.

According to such construction, it is possible to make large the crosssectional area of the openings 27, 27 and thereby to reduce thepulsations of the discharge pressure. The pulsation suppressing effectof the openings 27, 27' is further enhanced by the effect of the noisedamping chamber 43.

What is claimed is:

l. A swash plate type compressor comprising:

a casing,

a pair of cylinder blocks disposed immediately adjacent one another at aseparation plane in said casmg,

a drive shaft rotatably supported by said cylinder blocks for rotationabout an axis extending transverse to said separation plane,

a swash plate rotatable with said drive shaft and disposed in acrankcase formed by facing portions of said cylinder blocks, bearingmeans for rotatably supporting said drive shaft and swash plate beingdisposed in said crankcase,

cylinder bores formed in said cylinder blocks for accommodating axialsliding movement of pistons disposed therein in response to rotation ofsaid drive shaft and swash plate,

and an inlet opening for supplying a fluid medium to said compressor forcompression within said cylinder bores by said pistons,

wherein said inlet opening extends from outside said casing directlyinto said crankcase at said separation plane so that lubricant containedin said fluid medium is supplied directly to said bearings, said inletopening being formed by facing portions of said cylinder blocks, saidfacing portions extending from immediately adjacent said casing so as todirect said fluid medium and lubricant directly radially inwardly fromsaid casing to said crankcase and bearing means.

2. A swash plate compressor as defined in claim I, wherein the cylinderblocks each have three cylinder bores, and wherein three piston membersare slidably inserted one each in said cylinder bores.

3. A swash plate compressor as defined in claim 2, wherein saidcylindrical shell has a cylindrical shape over the full length thereofin the direction of the axis of rotation of the drive shaft.

4. A swash plate compressor as defined in claim 1, wherein an outlet fordischarging compressed gas from said compressor is disposed at saidplane separating said cylinder blocks.

5. A swash plate compressor as defined in claim 4, wherein all openingsand passages of said compressor are arranged symmetrically with respectto said plane separating said cylinder blocks to effect symmetrical flowof refrigerant gas and the like through the compressor.

6. A compressor according to claim 1, wherein said bearing means andsaid swash plate are disposed in said crankcase at respective oppositesides of said separation plane so that lubricant is substantiallysymmetrically supplied to said bearings.

7. A compressor according to claim 6, wherein said cylinder blocks aresymmetrical with respect to said separation plane.

8. A compressor according to claim 7, wherein an outlet for dischargingall of the compressed fluid medium from said compressor is disposed atsaid separation plane.

9. A compressor according to claim 8, wherein all fluid medium openingsand passages in said compressor are symmetrically arranged with respectto said separation plane such that flow of fluid medium through saidcompressor is symmetrical with resultant symmetrical thermal loadings ofthe compressor parts.

10. A compressor according to claim 6, wherein identical plate memberswith respective inlet and outlet openings are provided at respectiveoppositely facing outer ends of said cylinder blocks.

11. A compressor according to claim 10, wherein cover members areprovided on the outer ends of said plate members which include hollowspaces serving as respective high and low pressure spaces for fluidpassing through said compressor, said cover members having similarshaped hollow spaces formed therein.

12. A compressor according to claim 11, wherein said hollow spaces areformed as concentrical cylindrical spaces.

13. A compressor according to claim 12, wherein said casing exhibits anouter substantially cylindrical surface along the axial length thereof.

14. A compressor according to claim 1, wherein lubricating passages areprovided which communicate low pressure passages of said compressor withlubricant using parts of said compressor that are located outside ofsaid crankcase and inside of said casing.

15. A compressor according to claim 1, characterized in that a noisedamping chamber is formed between said casing and an auxiliary coverfixed to the central portion of the outer periphery of said casing andcharacterized in that an outlet pipe for connecting the outlet side ofthe compressor with a refrigeration cycle is connected to said auxiliarycover and further an opening communicating with said noise dampingchamber at one end and with a high pressure chamber of said compressorat the other end is formed in each of said cylinder blocks, thereby toform a high pressure passage.

16. A compressor according to claim 1, wherein said cylinder blocks areof similar shape such that they are interchangeable with one another.

1. A swash plate type compressor comprising: a casing, a pair ofcylinder blocks disposed immediately adjacent one another at aseparation plane in said casing, a drive shaft rotatably supported bysaid cylInder blocks for rotation about an axis extending transverse tosaid separation plane, a swash plate rotatable with said drive shaft anddisposed in a crankcase formed by facing portions of said cylinderblocks, bearing means for rotatably supporting said drive shaft andswash plate being disposed in said crankcase, cylinder bores formed insaid cylinder blocks for accommodating axial sliding movement of pistonsdisposed therein in response to rotation of said drive shaft and swashplate, and an inlet opening for supplying a fluid medium to saidcompressor for compression within said cylinder bores by said pistons,wherein said inlet opening extends from outside said casing directlyinto said crankcase at said separation plane so that lubricant containedin said fluid medium is supplied directly to said bearings, said inletopening being formed by facing portions of said cylinder blocks, saidfacing portions extending from immediately adjacent said casing so as todirect said fluid medium and lubricant directly radially inwardly fromsaid casing to said crankcase and bearing means.
 2. A swash platecompressor as defined in claim 1, wherein the cylinder blocks each havethree cylinder bores, and wherein three piston members are slidablyinserted one each in said cylinder bores.
 3. A swash plate compressor asdefined in claim 2, wherein said cylindrical shell has a cylindricalshape over the full length thereof in the direction of the axis ofrotation of the drive shaft.
 4. A swash plate compressor as defined inclaim 1, wherein an outlet for discharging compressed gas from saidcompressor is disposed at said plane separating said cylinder blocks. 5.A swash plate compressor as defined in claim 4, wherein all openings andpassages of said compressor are arranged symmetrically with respect tosaid plane separating said cylinder blocks to effect symmetrical flow ofrefrigerant gas and the like through the compressor.
 6. A compressoraccording to claim 1, wherein said bearing means and said swash plateare disposed in said crankcase at respective opposite sides of saidseparation plane so that lubricant is substantially symmetricallysupplied to said bearings.
 7. A compressor according to claim 6, whereinsaid cylinder blocks are symmetrical with respect to said separationplane.
 8. A compressor according to claim 7, wherein an outlet fordischarging all of the compressed fluid medium from said compressor isdisposed at said separation plane.
 9. A compressor according to claim 8,wherein all fluid medium openings and passages in said compressor aresymmetrically arranged with respect to said separation plane such thatflow of fluid medium through said compressor is symmetrical withresultant symmetrical thermal loadings of the compressor parts.
 10. Acompressor according to claim 6, wherein identical plate members withrespective inlet and outlet openings are provided at respectiveoppositely facing outer ends of said cylinder blocks.
 11. A compressoraccording to claim 10, wherein cover members are provided on the outerends of said plate members which include hollow spaces serving asrespective high and low pressure spaces for fluid passing through saidcompressor, said cover members having similar shaped hollow spacesformed therein.
 12. A compressor according to claim 11, wherein saidhollow spaces are formed as concentrical cylindrical spaces.
 13. Acompressor according to claim 12, wherein said casing exhibits an outersubstantially cylindrical surface along the axial length thereof.
 14. Acompressor according to claim 1, wherein lubricating passages areprovided which communicate low pressure passages of said compressor withlubricant using parts of said compressor that are located outside ofsaid crankcase and inside of said casing.
 15. A compressor according toclaim 1, characterized in that a noise damping chamber is formed betweensaid casing and an auxiliary cover fixed to the central portion of theouter pEriphery of said casing and characterized in that an outlet pipefor connecting the outlet side of the compressor with a refrigerationcycle is connected to said auxiliary cover and further an openingcommunicating with said noise damping chamber at one end and with a highpressure chamber of said compressor at the other end is formed in eachof said cylinder blocks, thereby to form a high pressure passage.
 16. Acompressor according to claim 1, wherein said cylinder blocks are ofsimilar shape such that they are interchangeable with one another.